Uplink transmission gaps in eMTC

ABSTRACT

Aspects of the present disclosure provide techniques and apparatus for uplink transmission gaps in enhanced machine type communications (eMTC). In one aspect, a method is provided which may be performed by a wireless device such as a user equipment (UE), which can be a low cost eMTC UE. The method generally includes transmitting a random access preamble, receiving a random access response in response to the random access preamble, transmitting an uplink message containing an indication of a capability of the UE to transmit using uplink gaps, and receiving signaling of configuration information regarding uplink gaps.

CROSS-REFERENCE TO RELATED APPLICATION & PRIORITY CLAIM

This application claims benefit of and priority to U.S. ProvisionalPatent Application Ser. No. 62/340,478, filed May 23, 2016, and U.S.Provisional Patent Application Ser. No. 62/384,703, filed Sep. 7, 2016,which are herein incorporated by reference in their entirety for allapplicable purposes.

BACKGROUND Field of the Disclosure

Certain aspects of the present disclosure generally relate to wirelesscommunications and, more particularly, to uplink transmission gaps inenhanced machine type communication(s) (eMTC).

Description of Related Art

Wireless communication systems are widely deployed to provide varioustypes of communication content such as voice, data, and so on. Thesesystems may be multiple-access systems capable of supportingcommunication with multiple users by sharing the available systemresources (e.g., bandwidth and transmit power). Examples of suchmultiple-access systems include code division multiple access (CDMA)systems, time division multiple access (TDMA) systems, frequencydivision multiple access (FDMA) systems, 3rd Generation PartnershipProject (3GPP) Long Term Evolution (LTE)/LTE-Advanced (LTE-A) systemsand orthogonal frequency division multiple access (OFDMA) systems.

Generally, a wireless multiple-access communication system cansimultaneously support communication for multiple wireless terminals.Each terminal communicates with one or more base stations (BSs) viatransmissions on the forward and reverse links. The forward link (ordownlink) refers to the communication link from the BSs to theterminals, and the reverse link (or uplink) refers to the communicationlink from the terminals to the BSs. This communication link may beestablished via a single-input single-output, multiple-inputsingle-output or a multiple-input multiple-output (MIMO) system.

A wireless communication network may include a number of BSs that cansupport communication for a number of wireless devices. Wireless devicesmay include user equipments (UEs). Machine type communications (MTC) mayrefer to communication involving at least one remote device on at leastone end of the communication and may include forms of data communicationwhich involve one or more entities that do not necessarily need humaninteraction. MTC UEs may include UEs that are capable of MTCcommunications with MTC servers and/or other MTC devices through PublicLand Mobile Networks (PLMN), for example. Wireless devices may includeInternet-of-Things (IoT) devices (e.g., narrowband IoT (NB-IoT)devices). IoT may refer to a network of physical objects, devices, or“things”. IoT devices may be embedded with, for example, electronics,software, or sensors and may have network connectivity, which enablethese devices to collect and exchange data.

Some next generation, NR, or 5G networks may include a number of basestations, each simultaneously supporting communication for multiplecommunication devices, such as UEs. In LTE or LTE-A network, a set ofone or more BSs may define an e NodeB (eNB). In other examples (e.g., ina next generation or 5G network), a wireless multiple accesscommunication system may include a number of distributed units (e.g.,edge units (EUs), edge nodes (ENs), radio heads (RHs), smart radio heads(SRHs), transmission reception points (TRPs), etc.) in communicationwith a number of central units (e.g., CU, central nodes (CNs), accessnode controllers (ANCs), etc.), where a set of one or more distributedunits (DUs), in communication with a CU, may define an access node(e.g., AN, a new radio base station (NR BS), a NR NB, a network node, agNB, a 5G BS, an access point (AP), etc.). A BS or DU may communicatewith a set of UEs on downlink channels (e.g., for transmissions from aBS or to a UE) and uplink channels (e.g., for transmissions from a UE toa BS or DU).

These multiple access technologies have been adopted in varioustelecommunication standards to provide a common protocol that enablesdifferent wireless devices to communicate on a municipal, national,regional, and even global level. NR (e.g., 5G radio access) is anexample of an emerging telecommunication standard. NR is a set ofenhancements to the LTE mobile standard promulgated by 3GPP. NR isdesigned to better support mobile broadband Internet access by improvingspectral efficiency, lowering costs, improving services, making use ofnew spectrum, and better integrating with other open standards usingOFDMA with a cyclic prefix (CP) on the downlink (DL) and on the uplink(UL) as well as support beamforming, MIMO antenna technology, andcarrier aggregation.

However, as the demand for mobile broadband access continues toincrease, there exists a need for further improvements in LTE, MTC, IoT,and NR technology. Preferably, these improvements should be applicableto other multi-access technologies and the telecommunication standardsthat employ these technologies.

SUMMARY

The systems, methods, and devices of the disclosure each have severalaspects, no single one of which is solely responsible for its desirableattributes. Without limiting the scope of this disclosure as expressedby the claims which follow, some features will now be discussed briefly.After considering this discussion, and particularly after reading thesection entitled “DETAILED DESCRIPTION” one will understand how thefeatures of this disclosure provide advantages that include improvedcommunications between access points and stations in a wireless network.

Certain aspects of the present disclosure generally relate to uplinktransmission gaps in enhanced/evolved machine type communication(s)(eMTC).

Certain aspects of the present disclosure provide a method, performed bya wireless device, such as a user equipment (UE). The method generallyincludes transmitting a random access preamble, receiving a randomaccess response, in response to the random access preamble, transmittingan uplink message containing an indication of a capability of the UE totransmit using uplink gaps, and receiving signaling of configurationinformation regarding uplink gaps.

Certain aspects of the present disclosure provide a method, performed bya wireless device, such as a base station (BS). The method generallyincludes receiving a random access preamble from a UE, transmitting arandom access response to the UE, in response to the random accesspreamble, receiving an uplink message from the UE containing anindication of a capability of the UE to transmit using uplink gaps, andtransmitting, to the UE, signaling of configuration informationregarding uplink gaps.

Certain aspects of the present disclosure provide an apparatus, such asa wireless device (e.g., a UE). The apparatus generally includes meansfor transmitting a random access preamble, means for receiving a randomaccess response, in response to the random access preamble, means fortransmitting an uplink message containing an indication of a capabilityof the UE to transmit using uplink gaps, and means for receivingsignaling of configuration information regarding uplink gaps.

Certain aspects of the present disclosure provide an apparatus, such asa wireless device (e.g., a BS). The apparatus generally includes meansfor receiving a random access preamble from a UE, means for transmittinga random access response to the UE, in response to the random accesspreamble, means for receiving an uplink message from the UE containingan indication of a capability of the UE to transmit using uplink gaps,and means for transmitting, to the UE, signaling of configurationinformation regarding uplink gaps.

Certain aspects of the present disclosure provide an apparatus, such asa wireless device (e.g., a UE). The apparatus generally includes atleast one processor configured to output for transmission a randomaccess preamble, obtain a random access response, in response to therandom access preamble, output for transmission an uplink messagecontaining an indication of a capability of the UE to transmit usinguplink gaps, and obtain signaling of configuration information regardinguplink gaps; and memory coupled with the at least one processor.

Certain aspects of the present disclosure provide an apparatus, such asa wireless device (e.g., a BS). The apparatus generally includes atleast one processor configured to obtain a random access preamble from aUE, output for transmission a random access response to the UE, inresponse to the random access preamble, obtain an uplink message fromthe UE containing an indication of a capability of the UE to transmitusing uplink gaps, and output for transmission, to the UE, signaling ofconfiguration information regarding uplink gaps; and memory coupled withthe at least one processor.

Certain aspects of the present disclosure provide a computer readablemedium having computer executable code stored thereon for wirelesscommunications by a wireless device, such as a UE. The computerexecutable code generally includes code for transmitting a random accesspreamble, code for receiving a random access response, in response tothe random access preamble, code for transmitting an uplink messagecontaining an indication of a capability of the UE to transmit usinguplink gaps, and code for receiving signaling of configurationinformation regarding uplink gaps.

Certain aspects of the present disclosure provide a computer readablemedium having computer executable code stored thereon for wirelesscommunications by a wireless device, such as a BS. The computerexecutable code generally includes code for receiving a random accesspreamble from a UE, code for transmitting a random access response tothe UE, in response to the random access preamble, code for receiving anuplink message from the UE containing an indication of a capability ofthe UE to transmit using uplink gaps, and code for transmitting, to theUE, signaling of configuration information regarding uplink gaps.

Numerous other aspects are provided including methods, apparatus,systems, computer program products, computer-readable medium, andprocessing systems. To the accomplishment of the foregoing and relatedends, the one or more aspects comprise the features hereinafter fullydescribed and particularly pointed out in the claims. The followingdescription and the annexed drawings set forth in detail certainillustrative features of the one or more aspects. These features areindicative, however, of but a few of the various ways in which theprinciples of various aspects may be employed, and this description isintended to include all such aspects and their equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above-recited features of the presentdisclosure can be understood in detail, a more particular description,briefly summarized above, may be had by reference to aspects, some ofwhich are illustrated in the appended drawings. It is to be noted,however, that the appended drawings illustrate only certain typicalaspects of this disclosure and are therefore not to be consideredlimiting of its scope, for the description may admit to other equallyeffective aspects.

FIG. 1 is a block diagram conceptually illustrating an example of awireless communication network, in accordance with certain aspects ofthe present disclosure.

FIG. 2 shows a block diagram conceptually illustrating an example of abase station (BS) in communication with a user equipment (UE) in awireless communications network, in accordance with certain aspects ofthe present disclosure.

FIG. 3 is a block diagram conceptually illustrating an example of aframe structure in a wireless communications network, in accordance withcertain aspects of the present disclosure.

FIG. 4 is a block diagram conceptually illustrating two exemplarysubframe formats with the normal cyclic prefix, in accordance withcertain aspects of the present disclosure.

FIG. 5 illustrates an exemplary subframe configuration, for example, forenhanced/evolved machine type communications (eMTC), in accordance withcertain aspects of the present disclosure.

FIG. 6 illustrates an example deployment of, for example, narrowbandInternet-of-Things (NB-IoT), in accordance with certain aspects of thepresent disclosure.

FIG. 7 illustrates an example logical architecture of a distributedradio access network (RAN), in accordance with certain aspects of thepresent disclosure.

FIG. 8 illustrates an example physical architecture of a distributedRAN, in accordance with certain aspects of the present disclosure.

FIG. 9 is a diagram illustrating an example of a downlink (DL)-centricsubframe, in accordance with certain aspects of the present disclosure.

FIG. 10 is a diagram illustrating an example of an uplink (UL)-centricsubframe, in accordance with certain aspects of the present disclosure.

FIG. 11 is a flow diagram illustrating example operations for uplink gapnegotiation by a UE, in accordance with certain aspects of the presentdisclosure.

FIG. 12 is a flow diagram illustrating example operations for uplinktransmission gap negotiation and configuration by a BS, in accordancewith certain aspects of the present disclosure.

FIG. 13 is an example call flow diagram illustrating example operationsfor uplink transmission gap negotiation and configuration, in accordancewith certain aspects of the present disclosure.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. It is contemplated that elements disclosed in one aspectmay be beneficially utilized on other aspects without specificrecitation.

DETAILED DESCRIPTION

Aspects of the present disclosure provide techniques for uplinktransmission gaps in, for example, enhanced/evolved machine typecommunications (eMTC). According to certain aspects, a user equipment(UE), which may be a low cost (LC) eMTC UE may transmit a random accesspreamble and receive a random access response. The UE may transmit anuplink message containing an indication of capability of the UEregarding uplink gaps and receive signaling of configuration informationregarding uplink gaps based, at least in part, on the indicatedcapability.

The techniques described herein may be used for various wirelesscommunication networks such as CDMA, TDMA, FDMA, OFDMA, SC-FDMA andother networks. The terms “network” and “system” are often usedinterchangeably. A CDMA network may implement a radio technology such asuniversal terrestrial radio access (UTRA), cdma2000, etc. UTRA includeswideband CDMA (WCDMA), time division synchronous CDMA (TD-SCDMA), andother variants of CDMA. cdma2000 covers IS-2000, IS-95 and IS-856standards. A TDMA network may implement a radio technology such asglobal system for mobile communications (GSM). An OFDMA network mayimplement a radio technology such as evolved UTRA (E-UTRA), ultra mobilebroadband (UMB), IEEE 802.11 (WiFi), IEEE 802.16 (WiMAX), IEEE 802.20,Flash-OFDM®, etc. UTRA and EUTRA are part of universal mobiletelecommunication system (UMTS). 3GPP Long Term Evolution (LTE) andLTE-Advanced (LTE-A), in both frequency division duplex (FDD) and timedivision duplex (TDD), are new releases of UMTS that use EUTRA, whichemploys OFDMA on the downlink and SC-FDMA on the uplink. UTRA, EUTRA,UMTS, LTE, LTE-A and GSM are described in documents from an organizationnamed “3rd Generation Partnership Project” (3GPP). cdma2000 and UMB aredescribed in documents from an organization named “3rd GenerationPartnership Project 2” (3GPP2). NR (e.g., 5G radio access) is an exampleof an emerging telecommunication standard. NR is a set of enhancementsto the LTE mobile standard promulgated by 3GPP. The techniques describedherein may be used for the wireless networks and radio technologiesmentioned above as well as other wireless networks and radiotechnologies. Certain aspects of the techniques are described below forLTE/LTE-Advanced, and LTE/LTE-Advanced terminology is used in much ofthe description below. LTE and LTE-A are referred to generally as LTE.

It is noted that while aspects may be described herein using terminologycommonly associated with 3G and/or 4G wireless technologies, aspects ofthe present disclosure can be applied in other generation-basedcommunication systems, such as 5G and later.

Example Wireless Communications Network

FIG. 1 illustrates an example wireless communication network 100, inwhich aspects of the present disclosure may be practiced. For example,techniques presented herein may be used for uplink transmissions gaps inenhanced/evolved machine type communications (eMTC). Wirelesscommunication network 100 includes user equipment (UEs) 120 and basestations (BSs) 110. UE 120 may be a low cost (LC) device, such as aneMTC UE. UE 120 may transmit a random access preamble to BS 110. UE 120may receive a random access response, in response to the preamble, fromBS 110. UE 120 may transmit an uplink message containing an indicationof capability of the UE 120 regarding uplink gaps, to BS 110. UE 120 canreceive signaling of configuration information regarding uplink gapsfrom BS 110.

Wireless communication network 100 may be an LTE network or some otherwireless network, such as new radio (NR) or 5G network. Wirelesscommunication network 100 may include a number of BSs 110 and othernetwork entities. A BS is an entity that communicates with UEs and mayalso be referred to as a Node B (NB), a enhanced/evolved NB (eNB), agNB, a 5G NB, an access point (AP), a NR BS, a transmission receptionpoint (TRP), etc. Each BS may provide communication coverage for aparticular geographic area. In 3GPP, the term “cell” can refer to acoverage area of a BS and/or a BS subsystem serving this coverage area,depending on the context in which the term is used.

A BS may provide communication coverage for a macro cell, a pico cell, afemto cell, and/or other types of cell. A macro cell may cover arelatively large geographic area (e.g., several kilometers in radius)and may allow unrestricted access by UEs with service subscription. Apico cell may cover a relatively small geographic area and may allowunrestricted access by UEs with service subscription. A femto cell maycover a relatively small geographic area (e.g., a home) and may allowrestricted access by UEs having association with the femto cell (e.g.,UEs in a closed subscriber group (CSG)). A BS for a macro cell may bereferred to as a macro BS. A BS for a pico cell may be referred to as apico BS. A BS for a femto cell may be referred to as a femto BS or ahome BS. In the example shown in FIG. 1, BS 110 a may be a macro BS fora macro cell 102 a, BS 110 b may be a pico BS for a pico cell 102 b, andBS 110 c may be a femto BS for a femto cell 102 c. A BS may support oneor multiple (e.g., three) cells. The terms “base station” and “cell” maybe used interchangeably herein.

Wireless communication network 100 may also include relay stations. Arelay station is an entity that can receive a transmission of data froman upstream station (e.g., a BS 110 or a UE 120) and send a transmissionof the data to a downstream station (e.g., a UE 120 or a BS 110). Arelay station may also be a UE that can relay transmissions for otherUEs. In the example shown in FIG. 1, relay station 110 d may communicatewith macro BS 110 a and UE 120 d in order to facilitate communicationbetween BS 110 a and UE 120 d. A relay station may also be referred toas a relay eNB, a relay base station, a relay, etc.

Wireless communication network 100 may be a heterogeneous network thatincludes BSs of different types, e.g., macro BSs, pico BSs, femto BSs,relay BSs, etc. These different types of BSs may have different transmitpower levels, different coverage areas, and different impact oninterference in wireless communication network 100. For example, macroBSs may have a high transmit power level (e.g., 5 to 40 Watts) whereaspico BSs, femto BSs, and relay BSs may have lower transmit power levels(e.g., 0.1 to 2 Watts).

Network controller 130 may couple to a set of BSs and may providecoordination and control for these BSs. Network controller 130 maycommunicate with the BSs via a backhaul. The BSs may also communicatewith one another, e.g., directly or indirectly via a wireless orwireline backhaul.

UEs 120 (e.g., 120 a, 120 b, 120 c) may be dispersed throughout wirelesscommunication network 100, and each UE may be stationary or mobile. A UEmay also be referred to as an access terminal, a terminal, a mobilestation, a subscriber unit, a station, a Customer Premises Equipment(CPE), etc. A UE may be a cellular phone (e.g., a smart phone), apersonal digital assistant (PDA), a wireless modem, a wirelesscommunication device, a handheld device, a laptop computer, a cordlessphone, a wireless local loop (WLL) station, a tablet, a camera, a gamingdevice, a netbook, a smartbook, an ultrabook, a medical device, medicalequipment, a biometric sensor/device, a wearable device such as a smartwatch, smart clothing, smart glasses, a smart wristband, and/or smartjewelry (e.g., a smart ring, a smart bracelet, etc.), an entertainmentdevice (e.g., a music device, a video device, a satellite radio, etc.),industrial manufacturing equipment, a global positioning system (GPS)device, or any other suitable device configured to communicate via awireless or wired medium. Some UEs may be considered machine-typecommunication (MTC) devices or enhanced/evolved MTC (eMTC) devices.MTC/eMTC UEs may be implemented as IoT UEs. IoT UEs include, forexample, robots/robotic devices, drones, remote devices, sensors,meters, monitors, cameras, location tags, etc., that may communicatewith a BS, another device (e.g., remote device), or some other entity. Awireless node may provide, for example, connectivity for or to a network(e.g., a wide area network such as Internet or a cellular network) via awired or wireless communication link.

One or more UEs 120 in the wireless communication network 100 may be anarrowband bandwidth UE. As used herein, devices with limitedcommunication resources, e.g. smaller bandwidth, may be referred togenerally as narrowband UEs. Similarly, legacy devices, such as legacyand/or advanced UEs (e.g., in LTE) may be referred to generally aswideband UEs. Generally, wideband UEs are capable of operating on alarger amount of bandwidth than narrowband UEs.

In FIG. 1, a solid line with double arrows indicates desiredtransmissions between a UE and a serving BS, which is a BS designated toserve the UE on the downlink and/or uplink. A dashed line with doublearrows indicates potentially interfering transmissions between a UE anda BS.

In general, any number of wireless networks may be deployed in a givengeographic area. Each wireless network may support a particular radioaccess technology (RAT) and may operate on one or more frequencies. ARAT may also be referred to as a radio technology, an air interface,etc. A frequency may also be referred to as a carrier, a frequencychannel, etc. Each frequency may support a single RAT in a givengeographic area in order to avoid interference between wireless networksof different RATs. In some cases, NR or 5G RAT networks may be deployed.

In some examples, access to the air interface may be scheduled, whereina scheduling entity (e.g., a BS 110) allocates resources forcommunication among some or all devices and equipment within its servicearea or cell. The scheduling entity may be responsible for scheduling,assigning, reconfiguring, and releasing resources for one or moresubordinate entities. For scheduled communication, subordinate entitiesutilize resources allocated by the scheduling entity. BSs 110 are notthe only entities that may function as a scheduling entity. In someexamples, UE 120 may function as a scheduling entity, schedulingresources for one or more subordinate entities (e.g., one or more otherUEs 120). In this example, the UE is functioning as a scheduling entity,and other UEs utilize resources scheduled by the UE for wirelesscommunication. A UE may function as a scheduling entity in apeer-to-peer (P2P) network, and/or in a mesh network. In a mesh networkexample, UEs may optionally communicate directly with one another inaddition to communicating with the scheduling entity.

Thus, in a wireless communication network with a scheduled access totime-frequency resources and having a cellular configuration, a P2Pconfiguration, and a mesh configuration, a scheduling entity and one ormore subordinate entities may communicate utilizing the scheduledresources.

FIG. 2 shows a block diagram of a design of BS 110 and UE 120, which maybe one of the BSs and one of the UEs illustrated in FIG. 1. BS 110 maybe equipped with T antennas 234 a through 234 t, and UE 120 may beequipped with R antennas 252 a through 252 r, where in general T≥1 andR≥1.

At BS 110, transmit processor 220 may receive data from data source 212for one or more UEs, select one or more modulation and coding schemes(MCS) for each UE based on channel quality indicators (CQIs) receivedfrom the UE, process (e.g., encode and modulate) the data for each UEbased on the MCS(s) selected for the UE, and provide data symbols forall UEs. Transmit processor 220 may also process system information(e.g., for static resource partitioning information (SRPI), etc.) andcontrol information (e.g., CQI requests, grants, upper layer signaling,etc.) and provide overhead symbols and control symbols. Processor 220may also generate reference symbols for reference signals (e.g., thecell-specific reference signal (CRS)) and synchronization signals (e.g.,the primary synchronization signal (PSS) and secondary synchronizationsignal (SSS)). Transmit (TX) multiple-input multiple-output (MIMO)processor 230 may perform spatial processing (e.g., precoding) on thedata symbols, the control symbols, the overhead symbols, and/or thereference symbols, if applicable, and may provide T output symbolstreams to T modulators (MODs) 232 a through 232 t. Each modulator 232may process a respective output symbol stream (e.g., for OFDM, etc.) toobtain an output sample stream. Each modulator 232 may further process(e.g., convert to analog, amplify, filter, and upconvert) the outputsample stream to obtain a downlink signal. T downlink signals frommodulators 232 a through 232 t may be transmitted via T antennas 234 athrough 234 t, respectively.

At UE 120, antennas 252 a through 252 r may receive the downlink signalsfrom BS 110 and/or other BSs and may provide received signals todemodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 may condition (e.g., filter, amplify, downconvert, anddigitize) its received signal to obtain input samples. Each demodulator254 may further process the input samples (e.g., for OFDM, etc.) toobtain received symbols. MIMO detector 256 may obtain received symbolsfrom all R demodulators 254 a through 254 r, perform MIMO detection onthe received symbols if applicable, and provide detected symbols.Receive processor 258 may process (e.g., demodulate and decode) thedetected symbols, provide decoded data for UE 120 to data sink 260, andprovide decoded control information and system information to acontroller/processor 280. A channel processor may determine referencesignal receive power (RSRP), reference signal strength indicator (RSSI),reference signal receive quality (RSRQ), CQI, etc.

On the uplink, at UE 120, transmit processor 264 may receive and processdata from data source 262 and control information (e.g., for reportscomprising RSRP, RSSI, RSRQ, CQI, etc.) from controller/processor 280.Processor 264 may also generate reference symbols for one or morereference signals. The symbols from transmit processor 264 may beprecoded by TX MIMO processor 266 if applicable, further processed bymodulators 254 a through 254 r (e.g., for SC-FDM, OFDM, etc.), andtransmitted to BS 110. At BS 110, the uplink signals from UE 120 andother UEs may be received by antennas 234, processed by demodulators232, detected by MIMO detector 236 if applicable, and further processedby receive processor 238 to obtain decoded data and control informationsent by UE 120. Processor 238 may provide the decoded data to data sink239 and the decoded control information to controller/processor 240. BS110 may include communication unit 244 and communicate to networkcontroller 130 via communication unit 244. Network controller 130 mayinclude communication unit 294, controller/processor 290, and memory292.

Controllers/processors 240 and 280 may direct the operation at BS 110and UE 120, respectively, to perform techniques presented herein forpower savings for control channel monitoring in enhanced machine typecommunications (eMTC). For example, processor 240 and/or otherprocessors and modules at BS 110, and processor 280 and/or otherprocessors and modules at UE 120, may perform or direct operations of BS110 and UE 120, respectively. For example, controller/processor 280and/or other controllers/processors and modules at UE 120, and/orcontroller/processor 240 and/or other controllers/processors and modulesat BS 110 may perform or direct operations 1100 and 1200 shown in FIGS.11 and 12, respectively. Memories 242 and 282 may store data and programcodes for BS 110 and UE 120, respectively. Scheduler 246 may scheduleUEs for data transmission on the downlink and/or uplink.

FIG. 3 shows an exemplary frame structure 300 for FDD in a wirelesscommunication system (e.g., LTE). The transmission timeline for each ofthe downlink and uplink may be partitioned into units of radio frames.Each radio frame may have a predetermined duration (e.g., 10milliseconds (ms)) and may be partitioned into 10 subframes with indicesof 0 through 9. Each subframe may include two slots. Each radio framemay thus include 20 slots with indices of 0 through 19. Each slot mayinclude L symbol periods, for example, seven symbol periods for a normalcyclic prefix (as shown in FIG. 3) or six symbol periods for an extendedcyclic prefix. The 2L symbol periods in each subframe may be assignedindices of 0 through 2L−1.

In certain wireless communication systems (e.g., LTE), a BS may transmita PSS and SSS on the downlink in the center of the system bandwidth foreach cell supported by the BS. The PSS and SSS may be transmitted insymbol periods 6 and 5, respectively, in subframes 0 and 5 of each radioframe with the normal cyclic prefix, as shown in FIG. 3. The PSS and SSSmay be used by UEs for cell search and acquisition. The BS may transmita CRS across the system bandwidth for each cell supported by the BS. TheCRS may be transmitted in certain symbol periods of each subframe andmay be used by the UEs to perform channel estimation, channel qualitymeasurement, and/or other functions. The BS may also transmit a physicalbroadcast channel (PBCH) in symbol periods 0 to 3 in slot 1 of certainradio frames. The PBCH may carry some system information. The BS maytransmit other system information such as system information blocks(SIBs) on a physical downlink shared channel (PDSCH) in certainsubframes. The BS may transmit control information/data on a physicaldownlink control channel (PDCCH) in the first B symbol periods of asubframe, where B may be configurable for each subframe. The BS maytransmit traffic data and/or other data on the PDSCH in the remainingsymbol periods of each subframe.

In certain systems (e.g., such as NR or 5G systems), a BS may transmitthese or other signals in these locations or in different locations ofthe subframe.

FIG. 4 shows two exemplary subframe formats 410 and 420 with the normalcyclic prefix. The available time frequency resources may be partitionedinto resource blocks (RBs). Each RB may cover 12 subcarriers in one slotand may include a number of resource elements (REs). Each RE may coverone subcarrier in one symbol period and may be used to send onemodulation symbol, which may be a real or complex value.

Subframe format 410 may be used for two antennas. A CRS may betransmitted from antennas 0 and 1 in symbol periods 0, 4, 7 and 11. Areference signal is a signal that is known a priori by a transmitter anda receiver and may also be referred to as pilot. A CRS is a referencesignal that is specific for a cell, e.g., generated based on a cellidentity (ID). In FIG. 4, for a given RE with label Ra, a modulationsymbol may be transmitted on that RE from antenna a, and no modulationsymbols may be transmitted on that RE from other antennas. Subframeformat 420 may be used with four antennas. A CRS may be transmitted fromantennas 0 and 1 in symbol periods 0, 4, 7 and 11 and from antennas 2and 3 in symbol periods 1 and 8. For both subframe formats 410 and 420,a CRS may be transmitted on evenly spaced subcarriers, which may bedetermined based on cell ID. CRSs may be transmitted on the same ordifferent subcarriers, depending on their cell IDs. For both subframeformats 410 and 420, REs not used for the CRS may be used to transmitdata (e.g., traffic data, control data, and/or other data).

The PSS, SSS, CRS and PBCH in LTE are described in 3GPP TS 36.211,entitled “Evolved Universal Terrestrial Radio Access (E-UTRA); PhysicalChannels and Modulation,” which is publicly available.

An interlace structure may be used for each of the downlink and uplinkfor FDD in certain systems (e.g., LTE). For example, Q interlaces withindices of 0 through Q−1 may be defined, where Q may be equal to 4, 6,8, 10, or some other value. Each interlace may include subframes thatare spaced apart by Q frames. In particular, interlace q may includesubframes q, q+Q, q+2Q, etc., where qϵ{0, . . . , Q−1}.

The wireless network may support hybrid automatic retransmission request(HARQ) for data transmission on the downlink and uplink. For HARQ, atransmitter (e.g., a BS) may send one or more transmissions of a packetuntil the packet is decoded correctly by a receiver (e.g., a UE) or someother termination condition is encountered. For synchronous HARQ, alltransmissions of the packet may be sent in subframes of a singleinterlace. For asynchronous HARQ, each transmission of the packet may besent in any subframe.

A UE may be located within the coverage of multiple BSs. One of theseBSs may be selected to serve the UE. The serving BS may be selectedbased on various criteria such as received signal strength, receivedsignal quality, pathloss, etc. Received signal quality may be quantifiedby a signal-to-noise-and-interference ratio (SINR), or a RSRQ, or someother metric. The UE may operate in a dominant interference scenario inwhich the UE may observe high interference from one or more interferingBSs. The wireless communication network may support a 180 kHz deploymentfor narrowband operation (e.g., NB-IoT) with different deployment modes.In one example, narrowband operations may be deployed in-band, forexample, using RBs within a wider system bandwidth. In one case,narrowband operations may use one RB within the wider system bandwidthof an existing network (e.g., such as an LTE network). In this case, the180 kHz bandwidth for the RB may have to be aligned with a wideband RB.In one example, narrowband operations may be deployed in the unused RBswithin a carrier guard-band (e.g., LTE). In this deployment, the 180 kHzRB within the guard band may be aligned with a 15 kHz tone grid ofwideband LTE, for example, in order to use the same Fast FourierTransform (FFT) and/or reduce interference in-band legacy LTEcommunications.

Example Narrowband eMTC

The focus of traditional LTE design (e.g., for legacy “non MTC” devices)is on the improvement of spectral efficiency, ubiquitous coverage, andenhanced quality of service (QoS) support. Current LTE system downlink(DL) and uplink (UL) link budgets are designed for coverage of high enddevices, such as state-of-the-art smartphones and tablets, which maysupport a relatively large DL and UL link budget.

However, as described above, one or more UEs in the wirelesscommunication network (e.g., wireless communication network 100) may bedevices that have limited communication resources, such as narrowbandUEs, as compared to other (wideband) devices in the wirelesscommunication network. For narrowband UEs, various requirements may berelaxed as only a limited amount of information may need to beexchanged. For example, maximum bandwidth may be reduced (relative towideband UEs), a single receive radio frequency (RF) chain may be used,peak rate may be reduced (e.g., a maximum of 1000 bits for a transportblock size), transmit power may be reduced, Rank 1 transmission may beused, and half duplex operation may be performed.

In some cases, if half-duplex operation is performed, MTC UEs may have arelaxed switching time to transition from transmitting to receiving (orreceiving to transmitting). For example, the switching time may berelaxed from 20 μs for regular UEs to 1 ms for MTC UEs. Release 12 MTCUEs may still monitor downlink (DL) control channels in the same way asregular UEs, for example, monitoring for wideband control channels inthe first few symbols (e.g., PDCCH) as well as narrowband controlchannels occupying a relatively narrowband, but spanning a length of asubframe (e.g., enhanced PDCCH or ePDCCH).

Certain standards (e.g., LTE Release 13) may introduce support forvarious additional MTC enhancements, referred to herein as enhanced MTC(or eMTC). For example, eMTC may provide MTC UEs with coverageenhancements up to 15 dB or better.

As illustrated in the subframe structure 500 of FIG. 5, eMTC UEs cansupport narrowband operation while operating in a wider system bandwidth(e.g., 1.4/3/5/10/15/20 MHz). In the example illustrated in FIG. 5, aconventional legacy control region 510 may span system bandwidth of afirst few symbols, while a narrowband region 530 of the system bandwidth(spanning a narrow portion of a data region 520) may be reserved for anMTC physical downlink control channel (referred to herein as an M-PDCCH)and for an MTC physical downlink shared channel (referred to herein asan M-PDSCH). In some cases, an MTC UE monitoring the narrowband regionmay operate at 1.4 MHz or 6 resource blocks (RBs).

However, as noted above, eMTC UEs may be able to operate in a cell witha bandwidth larger than 6 RBs. Within this larger bandwidth, each eMTCUE may still operate (e.g., monitor/receive/transmit) while abiding by a6-physical resource block (PRB) constraint. In some cases, differenteMTC UEs may be served by different narrowband regions (e.g., with eachspanning 6-PRB blocks). As the system bandwidth may span from 1.4 to 20MHz, or from 6 to 100 RBs, multiple narrowband regions may exist withinthe larger bandwidth. An eMTC UE may also switch or hop between multiplenarrowband regions in order to reduce interference.

Example Narrowband Internet-of-Things

The Internet-of-Things (IoT) may refer to a network of physical objects,devices, or “things”. IoT devices may be embedded with, for example,electronics, software, or sensors and may have network connectivity,which enable these devices to collect and exchange data. IoT devices maybe sensed and controlled remotely across existing networkinfrastructure, creating opportunities for more direct integrationbetween the physical world and computer-based systems and resulting inimproved efficiency, accuracy, and economic benefit. Systems thatinclude IoT devices augmented with sensors and actuators may be referredto cyber-physical systems. Cyber-physical systems may includetechnologies such as smart grids, smart homes, intelligenttransportation, and/or smart cities. Each “thing” (e.g., IoT device) maybe uniquely identifiable through its embedded computing system may beable to interoperate within existing infrastructure, such as Internetinfrastructure.

NB-IoT may refer to a narrowband radio technology specially designed forthe IoT. NB-IoT may focus on indoor coverage, low cost, long batterylife, and large number of devices. To reduce the complexity of UEs,NB-IoT may allow for narrowband deployments utilizing one PRB (e.g., 180kHz+20 kHz guard band). NB-IoT deployments may utilize higher layercomponents of certain systems (e.g., LTE) and hardware to allow forreduced fragmentation and cross compatibility with, for example, NB-LTEand/or eMTC.

FIG. 6 illustrates an example deployment 600 of NB-IoT, according tocertain aspects of the present disclosure. Three NB-IoT deploymentconfigurations include in-band, guard-band, and standalone. For thein-band deployment configuration, NB-IoT may coexist with a legacysystem (e.g., GSM, WCDMA, and/or LTE system(s)) deployed in the samefrequency band. For example, the wideband LTE channel may be deployed invarious bandwidths between 1.4 MHz to 20 MHz. As shown in FIG. 6, adedicated RB 602 within that bandwidth may be available for use byNB-IoT and/or the RBs 1204 may be dynamically allocated for NB-IoT. Asshown in FIG. 6, in an in-band deployment, one RB, or 200 kHz, of awideband channel (e.g., LTE) may be used for NB-IoT.

Certain systems (e.g., LTE) may include unused portions of the radiospectrum between carriers to guard against interference between adjacentcarriers. In some deployments, NB-IoT may be deployed in a guard band606 of the wideband channel.

In other deployments, NB-IoT may be deployed standalone (not shown). Ina standalone deployment, one 200 MHz carrier may be utilized to carryNB-IoT traffic and GSM spectrum may be reused.

Deployments of NB-IoT may include synchronization signals such as PSSfor frequency and timing synchronization and SSS to convey systeminformation. For NB-IoT operations, PSS/SSS timing boundaries may beextended as compared to the existing PSS/SSS frame boundaries in legacysystems (e.g., LTE), for example, from 10 ms to 40 ms. Based on thetiming boundary, a UE is able to receive a PBCH transmission, which maybe transmitted in subframe 0 of a radio frame.

Example NR/5G RAN Architecture

New radio (NR) may refer to radios configured to operate according to anew air interface (e.g., other than Orthogonal Frequency DivisionalMultiple Access (OFDMA)-based air interfaces) or fixed transport layer(e.g., other than Internet Protocol (IP)). NR may utilize OFDM with a CPon the uplink and downlink and include support for half-duplex operationusing TDD. NR may include Enhanced Mobile Broadband (eMBB) servicetargeting wide bandwidth (e.g. 80 MHz beyond), millimeter wave (mmW)targeting high carrier frequency (e.g. 60 GHz), massive MTC (mMTC)targeting non-backward compatible MTC techniques, and/or missioncritical targeting ultra reliable low latency communications (URLLC)service.

A single component carrier (CC) bandwidth of 100 MHZ may be supported.NR RBs may span 12 sub-carriers with a sub-carrier bandwidth of 75 kHzover a 0.1 ms duration. Each radio frame may consist of 50 subframeswith a length of 10 ms. Consequently, each subframe may have a length of0.2 ms. Each subframe may indicate a link direction (e.g., DL or UL) fordata transmission and the link direction for each subframe may bedynamically switched. Each subframe may include DL/UL data as well asDL/UL control data. UL and DL subframes for NR may be as described inmore detail below with respect to FIGS. 9 and 10.

Beamforming may be supported and beam direction may be dynamicallyconfigured. MIMO transmissions with precoding may also be supported.MIMO configurations in the DL may support up to 8 transmit antennas withmulti-layer DL transmissions up to 8 streams and up to 2 streams per UE.Multi-layer transmissions with up to 2 streams per UE may be supported.Aggregation of multiple cells may be supported with up to 8 servingcells. Alternatively, NR may support a different air interface, otherthan an OFDM-based interface. NR networks may include entities suchcentral units (CUs) or distributed units (DUs).

The NR RAN may include a CU and DUs. A NR BS (e.g., a NB, an eNB, a gNB,a 5G NB, a TRP, an AP, etc.) may correspond to one or multiple BSs. NRcells can be configured as access cells (ACells) or data only cells(DCells). For example, the RAN (e.g., a CU or DU) can configure thecells. DCells may be cells used for carrier aggregation or dualconnectivity, but not used for initial access, cellselection/reselection, or handover. In some cases DCells may nottransmit synchronization signals—in some case cases DCells may transmitsynchronization signals.

FIG. 7 illustrates an example logical architecture 700 of a distributedRAN, according to aspects of the present disclosure. 5G access node 706may include access node controller (ANC) 702. ANC 702 may be a CU of thedistributed RAN. The backhaul interface to the next generation corenetwork (NG-CN) 704 may terminate at ANC 702. The backhaul interface toneighboring next generation access nodes (NG-ANs) 710 may terminate atANC 702. ANC 702 may include one or more TRPs 708. As described above,TRP may be used interchangeably with “cell”, BS, NR BS, NB, eNB, 5G NB,gNB, AP, etc.

TRPs 708 may comprise a DU. TRPs 708 may be connected to one ANC (e.g.,ANC 702) or more than one ANC (not illustrated). For example, for RANsharing, radio as a service (RaaS), and service specific ANDdeployments, TRP 708 may be connected to more than one ANC. TRP 708 mayinclude one or more antenna ports. TRPs 708 may be configured toindividually (e.g., dynamic selection) or jointly (e.g., jointtransmission) serve traffic to a UE.

Logical architecture 700 may be used to illustrate fronthaul definition.The architecture may be defined that support fronthauling solutionsacross different deployment types. For example, logical architecture 700may be based on transmit network capabilities (e.g., bandwidth, latency,and/or jitter). Logical architecture 700 may share features and/orcomponents with LTE. According to aspects, NG-AN 710 may support dualconnectivity with NR. NG-AN 710 may share a common fronthaul for LTE andNR. Logical architecture 700 may enable cooperation between and amongTRPs 708. For example, cooperation may be preset within a TRP and/oracross TRPs via ANC 702. In some cases, no inter-TRP interface may beneeded/present.

A dynamic configuration of split logical functions may be present withinlogical architecture 700. The packet data convergence protocol (PDCP),radio link control (RLC), and medium access control (MAC) protocols maybe adaptably placed at ANC 702 or TRP 708.

FIG. 8 illustrates an example physical architecture 800 of a distributedRAN, according to aspects of the present disclosure. Centralized corenetwork unit (C-CU) 802 may host core network functions. C-CU 802 may becentrally deployed. C-CU 802 functionality may be offloaded (e.g., toadvanced wireless services (AWS)), in an effort to handle peak capacity.

Centralized RAN unit (C-RU) 804 may host one or more ANC functions.Optionally, C-RU 804 may host core network functions locally. C-RU 804may have distributed deployment. C-RU 804 may be closer to the networkedge.

DU 806 may host one or more TRPs. DU 806 may be located at edges of thenetwork with radio frequency (RF) functionality.

FIG. 9 is a diagram showing an example of a DL-centric subframe 900.DL-centric subframe 900 may include control portion 902. Control portion902 may exist in the initial or beginning portion of DL-centric subframe900. Control portion 902 may include various scheduling informationand/or control information corresponding to various portions ofDL-centric subframe 900. In some configurations, control portion 902 maybe a physical DL control channel (PDCCH), as shown in FIG. 9. DL-centricsubframe 900 may also include DL data portion 904. DL data portion 904may sometimes be referred to as the payload of DL-centric subframe 900.DL data portion 904 may include the communication resources utilized tocommunicate DL data from the scheduling entity (e.g., UE or BS) to thesubordinate entity (e.g., UE). In some configurations, DL data portion904 may be a physical DL shared channel (PDSCH).

DL-centric subframe 900 may also include common UL portion 906. CommonUL portion 906 may sometimes be referred to as an UL burst, a common ULburst, and/or various other suitable terms. Common UL portion 906 mayinclude feedback information corresponding to various other portions ofDL-centric subframe 900. For example, common UL portion 906 may includefeedback information corresponding to control portion 902. Non-limitingexamples of feedback information may include an acknowledgment (ACK)signal, a negative acknowledgment (NACK) signal, a HARQ indicator,and/or various other suitable types of information. Common UL portion906 may include additional or alternative information, such asinformation pertaining to random access channel (RACH) procedures,scheduling requests (SRs), and various other suitable types ofinformation. As illustrated in FIG. 9, the end of DL data portion 904may be separated in time from the beginning of common UL portion 906.This time separation may sometimes be referred to as a gap, a guardperiod, a guard interval, and/or various other suitable terms. Thisseparation provides time for the switch-over from DL communication(e.g., reception operation by the subordinate entity) to ULcommunication (e.g., transmission by the subordinate entity). One ofordinary skill in the art will understand that the foregoing is merelyone example of a DL-centric subframe and alternative structures havingsimilar features may exist without necessarily deviating from theaspects described herein.

FIG. 10 is a diagram showing an example of an UL-centric subframe 1000.UL-centric subframe 1000 may include control portion 1002. Controlportion 1002 may exist in the initial or beginning portion of UL-centricsubframe 1000. Control portion 1002 in FIG. 10 may be similar to controlportion 1002 described above with reference to FIG. 9. UL-centricsubframe 1000 may also include UL data portion 1004. UL data portion1004 may sometimes be referred to as the payload of UL-centric subframe1000. The UL portion may refer to the communication resources utilizedto communicate UL data from the subordinate entity (e.g., UE) to thescheduling entity (e.g., UE or BS). In some configurations, controlportion 1002 may be a PDCCH. In some configurations, the data portionmay be a physical uplink shared channel (PUSCH).

As illustrated in FIG. 10, the end of control portion 1002 may beseparated in time from the beginning of UL data portion 1004. This timeseparation may sometimes be referred to as a gap, guard period, guardinterval, and/or various other suitable terms. This separation providestime for the switch-over from DL communication (e.g., receptionoperation by the scheduling entity) to UL communication (e.g.,transmission by the scheduling entity). UL-centric subframe 1000 mayalso include common UL portion 1006. Common UL portion 1006 in FIG. 10may be similar to common UL portion 906 described above with referenceto FIG. 9. Common UL portion 1006 may additionally or alternativelyinclude information pertaining to CQI, sounding reference signals(SRSs), and various other suitable types of information. One of ordinaryskill in the art will understand that the foregoing is merely oneexample of an UL-centric subframe and alternative structures havingsimilar features may exist without necessarily deviating from theaspects described herein.

In some circumstances, two or more subordinate entities (e.g., UEs) maycommunicate with each other using sidelink signals. Real-worldapplications of such sidelink communications may include public safety,proximity services, UE-to-network relaying, vehicle-to-vehicle (V2V)communications, Internet of Everything (IoE) communications, IoTcommunications, mission-critical mesh, and/or various other suitableapplications. Generally, a sidelink signal may refer to a signalcommunicated from one subordinate entity (e.g., UE1) to anothersubordinate entity (e.g., UE2) without relaying that communicationthrough the scheduling entity (e.g., UE or BS), even though thescheduling entity may be utilized for scheduling and/or controlpurposes. In some examples, the sidelink signals may be communicatedusing a licensed spectrum (unlike wireless local area networks, whichtypically use an unlicensed spectrum).

A UE may operate in various radio resource configurations, including aconfiguration associated with transmitting pilots using a dedicated setof resources (e.g., a RRC dedicated state, etc.) or a configurationassociated with transmitting pilots using a common set of resources(e.g., an RRC common state, etc.). When operating in the RRC dedicatedstate, the UE may select a dedicated set of resources for transmitting apilot signal to a network. When operating in the RRC common state, theUE may select a common set of resources for transmitting a pilot signalto the network. In either case, a pilot signal transmitted by the UE maybe received by one or more network access devices, such as an AN, a DU,or portions thereof. Each receiving network access device may beconfigured to receive and measure pilot signals transmitted on thecommon set of resources, and also receive and measure pilot signalstransmitted on dedicated sets of resources allocated to the UEs forwhich the network access device is a member of a monitoring set ofnetwork access devices for the UE. One or more of the receiving networkaccess devices, or a CU to which receiving network access device(s)transmit the measurements of the pilot signals, may use the measurementsto identify serving cells for the UEs, or to initiate a change ofserving cell for one or more of the UEs.

Example Uplink Transmission Gaps in eMTC

As mentioned above, certain systems (e.g., Release 13 enhanced machinetype communication (eMTC) systems), may support narrowband operation(e.g., communications on a 6 resource block (RB) band) and half duplextransmissions/reception for up to, e.g., 15 dB coverage enhancements orbetter. These systems may reserve a portion of the system bandwidth foran MTC physical downlink control (MPDCCH). The MPDCCH may be transmittedin a narrowband, may use at least one subframe, and may rely ondemodulation reference signal (DMRS) demodulation. Coverage may beincreased by performing repetition/bundling of signals.

A user equipment (UE), which may be a low cost (LC) UE such as an eMTCUE may be configured for half-duplex operation. In half-duplexoperation, the UE may only support transmission in one direction at atime. Thus, the UE may not monitor for downlink transmissions (such asfor the MPDCCH) during the period that the UE transmits on the uplink.In some cases, the UE may transmit on the uplink for a long period(e.g., 2048 ms). Thus, the local oscillator (LO) of the UE may driftduring this uplink period, for example, due to temperature change. Sincethe UE is not monitoring downlink during this period, the UE may not beable to correct for the frequency offset due to the LO drift.

Some UEs may use uplink gaps to correct for the frequency offset. Forexample, if the uplink transmission period is longer than a thresholdduration (e.g., Y ms), the UE can stop uplink transmission for an uplinkgap period (e.g., X ms). During the uplink gap period (e.g., referred toas a transmission gap or uplink gap), the UE can obtain the downlinkfrequency error estimation and correct the uplink frequency error (e.g.,correct for the LO drift). However, some UEs may be configured withother mechanisms for correcting the frequency offset (e.g., such astemperature compensation) and, thus, may not need to use uplink gaps.

Therefore, it may be desirable for the uplink gaps to be enabled ordisabled (e.g., configured or not configured) for UEs, for example,based on whether the UE needs/uses uplink gaps for frequency errorcorrection. For example, it may be desirable for the UE to be able tosignal that the UE requests (e.g., needs, uses, supports, has acapability for) uplink transmission gaps so that uplink gaps can beconfigured by the network. Techniques for the UE to use or not useuplink gaps (e.g., without receiving an explicit configuration from thenetwork) are also desirable, for example, for initialization of theuplink transmission gaps, for example, in cases where the BS may notknow whether the UE desires the uplink transmission gaps.

Accordingly, techniques for uplink transmission gaps in eMTC aredesirable.

Techniques presented herein may be used for uplink transmission gaps ineMTC. In aspects, a UE (e.g., such as 120) which may be a LC device suchas an eMTC UE, can perform an uplink transmission gap capabilitynegotiation with the BS (e.g., such as BS 110).

Example Uplink Transmission Gap Negotiation

According to certain aspects, a two-step negotiation can be performedbetween the BS and UE. FIG. 11 is a flow diagram illustrating exampleoperations 1100 for uplink gap negotiation, in accordance with certainaspects of the present disclosure. Operations 1100 may be performed, forexample, by a UE (e.g., UE 120) which may be a low cost device such asan eMTC UE.

Operations 1100 may begin, at 1102, by transmitting (e.g., using gaps ornot using gaps) a random access preamble (e.g., a RACH Msg. 1). Therandom access preamble transmitted by the UE to the BS may be a physicalrandom access channel (PRACH) message (e.g., a Msg1/preamble). Since thePRACH is an initial transmission, the BS may not know whether or not theUE desires, supports, or is capable of, using uplink transmission gaps.Thus, the UE may always transmit the PRACH using uplink gaps, regardlessof capability. For non-contention based PRACH, the UE may transmit usinguplink gaps or not using gaps, depending on received signaling.

According to certain aspects, repetitions for PRACH transmission may notbe transmitted back to back. For example, for some PRACH configurations,the UE may only transmit a single preamble per radio frame. In suchcases, the UE may not desire uplink transmission gaps. According tocertain aspects, the use of gaps for PRACH transmission may depend on atotal transmission time of the random access preamble, the maximumnumber of PRACH transmissions, and/or the separation between tworepetitions of PRACH. For example, if there is a separation of 3 msbetween two PRACH transmissions, then the UE may not need gaps (e.g.,because it can retune to downlink, stay in downlink for 1 ms to getfrequency error estimation, and retune to uplink again).

At 1104, the UE receives a random access response (e.g., a RACH Msg. 2),in response to the random access preamble.

At 1106, the UE transmits an uplink message (e.g., a RACH Msg3 and/or aMsg5) containing an indication of a capability of the UE to transmitusing uplink gaps (e.g., a request to use uplink gaps between repeateduplink transmissions). For example, the UE may respond to RAR from theBS by sending the RACH procedure Msg3 transmission to the BS. Accordingto certain aspects, the Msg3 transmission may include the indication(e.g., 1 bit) of the capability of the UE to transmit using uplink gaps.For example, the UE may send a request for uplink transmission gaps(e.g., a first step in the two-step negotiation). In aspects, theindication may be included only in frequency division duplexing (FDD)cells and, in this case, the bit may be reserved/unused in time divisionduplexing (TDD) cells. Alternatively, the indication/request may beprovided in a different message, such as a Msg. 5 after the RACHprocedure (e.g., an RRC message after the UE connects to the cell).

At 1108, the UE receives signaling (e.g., via RRC signaling or higherlayer/semi-static signaling) of configuration information regardinguplink gaps (e.g., RACH Msg. 4 or a different message). According tocertain aspects, the UE may transmit a physical uplink shared channel(PUSCH), a physical uplink control channel (PUCCH), and/or a physicalrandom access channel (PRACH), in accordance with the configurationinformation regarding uplink gaps.

As mentioned above, the signaling of the configuration informationregarding uplink gaps may be received in a Msg. 4 transmission (e.g., anRRC configuration/reconfiguration message or security activationmessage) from the BS. Alternatively, the configuration informationregarding uplink gaps may be received in a different (e.g., later)message, for example, after the Msg. 5 sent by the UE.

The configuration information may configure the UE to use uplinktransmission gaps. For example, if the uplink message from the UE (e.g.,the Msg. 3 or Msg. 5) indicates that the UE desires (e.g., requests,supports as a capability, etc.) transmission gaps, the UE may expect toreceive configuration information from the BS (e.g., the Msg. 4 RRCconfiguration or other message) configuring the UE for use of uplinktransmission gaps (e.g., the second step in the two-step negotiation);however, if the uplink message from the UE indicates that the UE doesnot desire (request, support of a capability, etc.) uplink transmissiongaps, the network may still decide to configure the UE with uplinktransmission gaps or may not configure with the UE with uplinktransmission gaps.

In some cases, the configuration information regarding the uplink gapsfor the UE can be provided by the BS implicitly. For example, the UE maytransmit an indication of whether or not the UE requests/supports uplinktransmission gaps (e.g., 1 bit in message 3 or message 5), and the UEmay start operating according to this indication after reception of alater message from the BS (e.g., after reception of Msg. 4 if the UEprovided its indication in Msg. 3, or after reception of Msg. 6 (RRCreconfiguration and/or security activation), if the provided itsindication in Msg. 5, etc.). In some cases, the reception of this latermessage can be detected by higher layers (e.g., RRC), and afterreception of this message the higher layers may deliver a message to thephysical layer indicating whether gaps are to be used or not. Uplinktransmission gaps may be requested based on UE's capability to handleuplink transmission gaps. Similarly, the uplink gap configuration may beset based on UE's capability to handle uplink transmission gaps.

According to certain aspects, the UE may transmit PUSCH, PUCCH and/orPRACH transmissions with or without transmission gaps, for example,according to the configuration from the eNB.

As mentioned above, the uplink message from the UE may be provided asthe Msg. 3 or Msg. 5. According to certain aspects, the UE may providethe indication of gap capability, request for gaps, in both the Msg. 3and the later message (e.g., the Msg5). In this case, the indication inthe later message may be consistent with the indication in the earliermessage (e.g., in the Msg3).

FIG. 12 is a flow diagram illustrating example operations 1200 foruplink transmission gap negotiation and configuring, in accordance withcertain aspects of the present disclosure. Operations 1200 may beperformed, for example, by a BS (e.g., BS 110). Operations 1200 may becomplementary operations by the BS to the operations 1100 performed bythe UE. Operations 1200 may begin, at 1202, by receiving a random accesspreamble from a UE. At 1204, the BS transmits a random access responseto the UE, in response to the random access preamble. At 1206, the BSreceives an uplink message from the UE containing an indication of acapability of the UE to transmit using uplink gaps. At 1208, the BStransmits, to the UE, signaling of configuration information regardinguplink gaps.

FIG. 13 is an example call flow diagram illustrating example operationsfor uplink transmission gap negotiation and configuration, in accordancewith certain aspects of the present disclosure. As shown in FIG. 13, UE1302 (e.g., UE 120) can send a Msg. 1 random access preamble with orwithout using uplink gaps. BS 1304 (e.g., BS 110) can respond with theMsg. 2 RAR. UE 1302 then sends the Msg. 3 RRC Connection Request which,in a first example, may include the indication of the UE's uplink gapcapability (or request for uplink gaps). BS 1304 then sends the Msg. 4RRC Connection Setup which, according to the first example, includesuplink gap configuration information for UE 1302. After the RACHprocedure, scheduled RRC transmissions can occur. In a second example,UE 1302 may send the uplink gap capability indication in a Msg. 5 and BS1304 sends Msg. 6 with the uplink gap configuration information for UE1302. In some cases, UE 1302 may provide the indication in both the Msg.3 and the Msg. 5. In some cases, uplink gap configuration informationmay be provided to the UE via higher layer signaling, without anexplicit indication from BS 1304.

Moreover, the term “or” is intended to mean an inclusive “or” ratherthan an exclusive “or.” That is, unless specified otherwise, or clearfrom the context, the phrase, for example, “X employs A or B” isintended to mean any of the natural inclusive permutations. That is, forexample the phrase “X employs A or B” is satisfied by any of thefollowing instances: X employs A; X employs B; or X employs both A andB. As used herein, reference to an element in the singular is notintended to mean “one and only one” unless specifically so stated, butrather “one or more.” For example, the articles “a” and “an” as used inthis application and the appended claims should generally be construedto mean “one or more” unless specified otherwise or clear from thecontext to be directed to a singular form. Unless specifically statedotherwise, the term “some” refers to one or more. A phrase referring to“at least one of” a list of items refers to any combination of thoseitems, including single members. As an example, “at least one of: a, b,or c” is intended to cover: a, b, c, a-b, a-c, b-c, and a-b-c, as wellas any combination with multiples of the same element (e.g., a-a, a-a-a,a-a-b, a-a-c, a-b-b, a-c-c, b-b, b-b-b, b-b-c, c-c, and c-c-c or anyother ordering of a, b, and c). As used herein, including in the claims,the term “and/or,” when used in a list of two or more items, means thatany one of the listed items can be employed by itself, or anycombination of two or more of the listed items can be employed. Forexample, if a composition is described as containing components A, B,and/or C, the composition can contain A alone; B alone; C alone; A and Bin combination; A and C in combination; B and C in combination; or A, B,and C in combination.

As used herein, the term “identifying” encompasses a wide variety ofactions. For example, “identifying” may include calculating, computing,processing, deriving, investigating, looking up (e.g., looking up in atable, a database or another data structure), ascertaining and the like.Also, “identifying” may include receiving (e.g., receiving information),accessing (e.g., accessing data in a memory) and the like. Also,“identifying” may include resolving, selecting, choosing, establishingand the like.

In some cases, rather than actually communicating a frame, a device mayhave an interface to communicate a frame for transmission or reception.For example, a processor may output a frame, via a bus interface, to anRF front end for transmission. Similarly, rather than actually receivinga frame, a device may have an interface to obtain a frame received fromanother device. For example, a processor may obtain (or receive) aframe, via a bus interface, from an RF front end for transmission.

The methods disclosed herein comprise one or more steps or actions forachieving the described method. The method steps and/or actions may beinterchanged with one another without departing from the scope of theclaims. In other words, unless a specific order of steps or actions isspecified, the order and/or use of specific steps and/or actions may bemodified without departing from the scope of the claims.

The various operations of methods described above may be performed byany suitable means capable of performing the corresponding functions.The means may include various hardware and/or software component(s)and/or module(s), including, but not limited to a circuit, anapplication specific integrated circuit (ASIC), or processor. Softwareshall be construed broadly to mean instructions, instruction sets, code,code segments, program code, programs, subprograms, software modules,applications, software applications, software packages, firmware,routines, subroutines, objects, executables, threads of execution,procedures, functions, etc., whether referred to as software, firmware,middleware, microcode, hardware description language, or otherwise.Generally, where there are operations illustrated in Figures, thoseoperations may be performed by any suitable corresponding counterpartmeans-plus-function components.

For example, means for determining, means for performing, means forsetting, means for processing, means for obtaining, means fortransmitting, means for receiving, means for sending, means forsignaling, and/or means for transmitting may include one or moreprocessors, transmitters, receivers, antennas, and/or other elements ofthe user equipment 120 and/or the base station 110 illustrated in FIG.2.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or combinations thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, software, or combinations thereof. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, circuits, and steps have been describedabove generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a digital signal processor (DSP), anapplication specific integrated circuit (ASIC), a field programmablegate array (FPGA) or other programmable logic device, discrete gate ortransistor logic, discrete hardware components, or any combinationthereof designed to perform the functions described herein. Ageneral-purpose processor may be a microprocessor, but in thealternative, the processor may be any conventional processor,controller, microcontroller, or state machine. A processor may also beimplemented as a combination of computing devices, e.g., a combinationof a DSP and a microprocessor, a plurality of microprocessors, one ormore microprocessors in conjunction with a DSP core, or any other suchconfiguration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination thereof. A softwaremodule may reside in RAM memory, flash memory, ROM memory, EPROM memory,EEPROM memory, phase change memory, registers, hard disk, a removabledisk, a CD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, or combinations thereof. Ifimplemented in software, the functions may be stored on or transmittedover as one or more instructions or code on a computer-readable medium.Computer-readable media includes both computer storage media andcommunication media including any medium that facilitates transfer of acomputer program from one place to another. A storage media may be anyavailable media that can be accessed by a general purpose or specialpurpose computer. By way of example, and not limitation, suchcomputer-readable media can comprise RAM, ROM, EEPROM, CD/DVD or otheroptical disk storage, magnetic disk storage or other magnetic storagedevices, or any other medium that can be used to carry or store desiredprogram code means in the form of instructions or data structures andthat can be accessed by a general-purpose or special-purpose computer,or a general-purpose or special-purpose processor. Also, any connectionis properly termed a computer-readable medium. For example, if thesoftware is transmitted from a website, server, or other remote sourceusing a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and Blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. A method for wireless communications by a userequipment (UE), comprising: transmitting a random access preamble;receiving a random access response, in response to the random accesspreamble; transmitting an uplink message, wherein the uplink messagecontains an indication of a capability of the UE to transmit uplinktransmissions using an uplink gap between the uplink transmissions, andwherein the indication of the capability of the UE to transmit theuplink transmissions using the uplink gap is an indication in the uplinkmessage indicating whether use of the uplink gap between the uplinktransmissions is supported or requested by the UE; and transmitting theuplink transmissions using the uplink gap between the uplinktransmissions based on the indicated capability of the UE, whereintransmitting the uplink transmissions using the uplink gap comprisesstopping uplink transmission for an uplink gap period when an uplinktransmission period is longer than a threshold duration.
 2. The methodof claim 1, further comprising: receiving a message via higher layersignaling, wherein the message does not contain explicit uplink gapconfiguration; and setting an uplink gap configuration based on thecapability of the UE to transmit the uplink transmissions using theuplink gap.
 3. The method of claim 2, wherein the message received viathe higher layer signaling comprises at least one of: a radio resourcecontrol (RRC) reconfiguration message or a security activation message.4. The method of claim 2, further comprising: processing the messagereceived via the higher layer signaling in higher layers; and receivingan indication from the higher layers, at a physical layer, of the uplinkgap configuration.
 5. The method of claim 1, wherein transmitting theuplink transmissions comprises: transmitting at least one of: a physicaluplink shared channel (PUSCH) or a physical uplink control channel(PUCCH).
 6. The method of claim 1, wherein one or more of the uplinktransmissions are repeated uplink transmissions.
 7. The method of claim1, further comprising receiving signaling of configuration informationregarding uplink gaps via radio resource control (RRC) signaling.
 8. Themethod of claim 1, wherein transmitting the random access preamblecomprises: transmitting the random access preamble using uplink gaps orwithout using uplink gaps based, at least in part, on at least one of: atotal transmission time of the random access preamble, a separationbetween two repetitions of the random access preamble, or configurationinformation regarding uplink gaps.
 9. The method of claim 1, wherein atleast one of: the uplink message or the random access preamble istransmitted using uplink gaps regardless of the indicated capability ofthe UE to transmit the uplink transmissions using the uplink gap.
 10. Amethod for wireless communications by a base station (BS), comprising:receiving a random access preamble from a user equipment (UE);transmitting a random access response to the UE, in response to therandom access preamble; receiving an uplink message from the UE, whereinthe uplink message contains an indication of a capability of the UE totransmit uplink transmissions using an uplink gap between the uplinktransmissions, and wherein the indication of the capability of the UE totransmit the uplink transmissions using the uplink gap is an indicationin the uplink message indicating whether use of the uplink gap betweenthe uplink transmissions is supported or requested by the UE; andreceiving the uplink transmissions, wherein the uplink transmissionsinclude the uplink gap after an uplink transmission period is longerthan a threshold duration.
 11. The method of claim 10, furthercomprising: transmitting, to the UE, a message via higher layersignaling, wherein the message does not contain explicit uplink gapconfiguration.
 12. The method of claim 10, wherein one or more of theuplink transmissions are repeated uplink transmissions.
 13. The methodof claim 10, further comprising: transmitting, to the UE, signaling ofconfiguration information regarding uplink gaps via radio resourcecontrol (RRC) signaling.
 14. The method of claim 10, wherein: receivingthe uplink transmissions comprises receiving at least one of: a physicaluplink shared channel (PUSCH) or a physical uplink control channel(PUCCH).
 15. An apparatus for wireless communications by a userequipment (UE), comprising: means for transmitting a random accesspreamble; means for receiving a random access response, in response tothe random access preamble; means for transmitting an uplink message,wherein the uplink message contains an indication of a capability of theUE to transmit uplink transmissions using an uplink gap between theuplink transmissions, and wherein the indication of the capability ofthe UE to transmit the uplink transmissions using the uplink gap is anindication in the uplink message indicating whether use of the uplinkgap between the uplink transmissions is supported or requested by theUE; and means for transmitting the uplink transmissions using the uplinkgap between the uplink transmissions based on the indicated capabilityof the UE, wherein the means for transmitting the uplink transmissionsusing the uplink gap comprises means for stopping uplink transmissionfor an uplink gap period when an uplink transmission period is longerthan a threshold duration.
 16. The apparatus of claim 15, furthercomprising: means for receiving a message via higher layer signaling,wherein the message does not contain explicit uplink gap configuration;and means for setting an uplink gap configuration based on thecapability of the UE to transmit the uplink transmissions using theuplink gap.
 17. The apparatus of claim 16, wherein the message receivedvia the higher layer signaling comprises at least one of: a radioresource control (RRC) reconfiguration message or a security activationmessage.
 18. The apparatus of claim 16, further comprising: means forprocessing the message received via the higher layer signaling in higherlayers; and means for receiving an indication from the higher layers, ata physical layer, of the uplink gap configuration.
 19. The apparatus ofclaim 15, wherein the means for transmitting the uplink transmissionscomprises: means for transmitting at least one of: a physical uplinkshared channel (PUSCH) or a physical uplink control channel (PUCCH). 20.The apparatus of claim 15, wherein one or more of the uplinktransmissions are repeated uplink transmissions.
 21. The apparatus ofclaim 15, wherein the further comprising means for receiving signalingof configuration information regarding uplink gaps via radio resourcecontrol (RRC) signaling.
 22. The apparatus of claim 15, wherein themeans for transmitting the random access preamble comprises: means fortransmitting the random access preamble using gaps or without using gapsbased, at least in part, on at least one of: a total transmission timeof the random access preamble, a separation between two repetitions ofthe random access preamble, or configuration information regardinguplink gaps.
 23. The apparatus of claim 15, wherein at least one of: theuplink message or the random access preamble is transmitted using uplinkgaps regardless of the indicated capability of the UE to transmit theuplink transmissions using the uplink gap.
 24. An apparatus for wirelesscommunications by a base station (BS), comprising: means for receiving arandom access preamble from a user equipment (UE); means fortransmitting a random access response to the UE, in response to therandom access preamble; means for receiving an uplink message from theUE, wherein the uplink message contains an indication of a capability ofthe UE to transmit uplink transmissions using an uplink gap between theuplink transmissions, and wherein the indication of the capability ofthe UE to transmit the uplink transmissions using the uplink gap is anindication in the uplink message indicating whether use of the uplinkgap between the uplink transmissions is supported or requested by theUE; and means for receiving the uplink transmissions, wherein the uplinktransmissions include the uplink gap after an uplink transmission periodis longer than a threshold duration.
 25. The apparatus of claim 24,further comprising: means for transmitting, to the UE, a message viahigher layer signaling, wherein the message does not contain explicituplink gap configuration.
 26. The apparatus of claim 24, wherein the oneor more uplink transmissions are repeated uplink transmissions.
 27. Theapparatus of claim 24, further comprising: means for transmitting, tothe UE, signaling of configuration information regarding uplink gaps viaradio resource control (RRC) signaling.
 28. The apparatus of claim 24,means for wherein: means for receiving the uplink transmission comprisesreceiving at least one of: a physical uplink shared channel (PUSCH) or aphysical uplink control channel (PUCCH).
 29. An apparatus for wirelesscommunications by a user equipment (UE), comprising: at least oneprocessor coupled with a memory and configured to: transmit a randomaccess preamble; receive a random access response, in response to therandom access preamble; transmit an uplink message, wherein the uplinkmessage contains an indication of a capability of the UE to transmituplink transmissions using an uplink gap between the uplinktransmissions, and wherein the indication of the capability of the UE totransmit the uplink transmissions using the uplink gap is an indicationin the uplink message indicating whether use of the uplink gap betweenthe uplink transmissions is supported or requested by the UE; andtransmit the uplink transmissions using the uplink gap between theuplink transmissions based on the indicated capability of the UE,wherein the at least one processor is configured to transmit the uplinktransmissions using the uplink gap by being configured to stop uplinktransmission for an uplink gap period when an uplink transmission periodis longer than a threshold duration.
 30. The apparatus of claim 29,wherein the at least one processor is configured to transmit at leastone of: the uplink message or the random access preamble using uplinkgaps regardless of the indicated capability of the UE to transmit theuplink transmissions using the uplink gap.
 31. The method of claim 1,wherein the uplink gap comprises a period for the UE to obtain adownlink frequency error estimation.
 32. The method of claim 1, furthercomprising: monitoring for a downlink transmission during the uplinkgap; obtaining a downlink frequency error estimation during the uplinkgap; and correcting an uplink frequency error.
 33. The method of claim1, wherein the indication in the uplink message is a 1-bit indication.34. The method of claim 1, wherein the uplink message indicates use ofuplink gaps is supported or requested for half-duplex frequency divisionduplexing (FDD).
 35. The method of claim 1, wherein the capability ofthe UE to transmit the uplink transmissions using the uplink gapcomprises a capability of the UE to: stop uplink transmission for theuplink gap period after performing uplink transmission for the thresholdduration; and resume uplink transmission after the uplink gap period.